基于J2ME的移动位置服务3G手机应用平台的设计

提出如何运用J2ME及SVG Tiny构造3C手机LBS终端应用平台，重点阐述了屏幕导航模型的设计、网络连接通信、电子地图的处理及数据的持久化处理等。本平台融合了GIS与3G、J2ME及SVG技术，以J2ME为开发平台，结合空间数据以SVG为地图显示介质，在3G手机中实现方便、快捷、精确的移动位置服务。  

基于移动计算环境的GIS研究

数字移动通信、互联网的发展与整合，使移动计算很快成为主流计算环境，GIS作为IT行业最重要的信息技术之一，提供面向移动计算环境的信息服务是必然的发展趋势。本文首先介绍了GIS的发展历程，接着分析了移动计算环境的概念和特点，在此基础上讨论了在移动计算环境下GIS的主要发展方向和关键技术，最后以空间定位信息服务（LBS）为例研究了GIS在移动环境中的应用。  

基于移动计算的地理信息系统的发展研究及应用前景

计算机与通信技术使得移动计算成为当今一种主流计算方法，基于移动计算的地理信息系统（称做移动GIS）就是在这种条件下产生的。可以预见，移动地理信息系统将会是GIS产业发展的下一个亮点。本用GIS发展的观点叙述了移动GIS发展的必然性，以及移动GIS发展过程中的变化和特点，并且讨论了移动GIS的关键技术及应用前景。  

位置隐私研究综述

近年来随着传感器和无线移动设备的飞速发展,随时随地获得个人位置成为可能。一方面,促进了基于位置服务的飞速发展,另一方面,个人位置隐私泄露的问题引起人们的广泛关注。由于移动环境中位置信息的特殊性,造成无法直接利用现有的关系数据库隐私保护技术。文章分析了位置隐私保护中存在的挑战问题,从系统结构、位置匿名技术和查询处理技术三方面归纳总结了现有的研究工作,并指出了未来的研究方向。  

位置服务隐私保护研究综述

由于位置感知移动电子设备的繁荣,位置服务(LBS)几乎在所有的社会和商业领域广泛流行.虽然LBS给个人和社会带来了巨大利益,但也给用户的隐私造成了严重威胁.因为用户享受LBS的同时需要向不可信的LBS提供商泄露其位置和查询属性,而附加在这些信息上的上下文揭露了用户的兴趣爱好、生活习惯、健康状况等.如何保护用户的隐私免受恶意提供商的侵犯,对LBS生态系统的健康发展至关重要,因而引起了研究者的广泛关注.对LBS隐私保护的研究现状与进展进行综述.首先介绍LBS隐私的概念和威胁模型;然后,从系统结构、度量指标、保护技术等方面对现有的研究工作进行细致的分类归纳和阐述,重点阐述当前LBS隐私保护研究的主流技术:基于扭曲法的隐私保护技术;通过对各类技术性能和优缺点的分析比较,指出了LBS隐私保护研究存在的问题及可能的解决方法;最后,对未来研究方向进行了展望.  

Multidimensional data modeling for location-based services

With the recent and continuing advances in areas such as wireless communications and positioning technologies, mobile, location-based services are becoming possible.Such services deliver location-dependent content to their users. More specifically, these services may capture the movements and requests of their users in multidimensional databases, i.e., data warehouses, and content delivery may be based on the results of complex queries on these data warehouses. Such queries aggregate detailed data in order to find useful patterns, e.g., in the interaction of a particular user with the services.The application of multidimensional technology in this context poses a range of new challenges. The specific challenge addressed here concerns the provision of an appropriate multidimensional data model. In particular, the paper extends an existing multidimensional data model and algebraic query language to accommodate spatial values that exhibit partial containment relationships instead of the total containment relationships normally assumed in multidimensional data models. Partial containment introduces imprecision in aggregation paths. The paper proposes a method for evaluating the imprecision of such paths. The paper also offers transformations of dimension hierarchies with partial containment relationships to simple hierarchies, to which existing precomputation techniques are applicable.Received: 28 September 2002, Accepted: 5 April 2003, Published online: 12 August 2003Edited by: J. Veijalainen Correspondence to: I. Timko  

Nearest and reverse nearest neighbor queries for moving objects

With the continued proliferation of wireless communications and advances in positioning technologies, algorithms for efficiently answering queries about large populations of moving objects are gaining interest. This paper proposes algorithms for k nearest and reverse k nearest neighbor queries on the current and anticipated future positions of points moving continuously in the plane. The former type of query returns k objects nearest to a query object for each time point during a time interval, while the latter returns the objects that have a specified query object as one of their k closest neighbors, again for each time point during a time interval. In addition, algorithms for so-called persistent and continuous variants of these queries are provided. The algorithms are based on the indexing of object positions represented as linear functions of time. The results of empirical performance experiments are reported.  

Pervasive location acquisition technologies: Opportunities and challenges for geospatial studies

The rapid development and increasing availability of various location acquisition technologies provide geospatial studies with both opportunities and challenges. These opportunities and challenges are discussed in this paper focusing on the following three aspects: the massive acquisition of location data and data quality, the analysis of massive location data and pattern discovery, and privacy protection for massive location data. This paper examines the current status of and the potential opportunities for geospatial research in these three areas and notes the major challenges. Finally, the development of this special issue is described, and the four articles included in this special issue are presented.  

Modeling Costs of Turns in Route Planning

In this paper a model that handles costs of turns in route planning is defined, investigated and discussed. Costs are traditionally attached to edges in a graph. For some important route planning problems other costs can be identified, namely costs that appear when leaving one edge and entering the next. Examples are turn restrictions, the turning angle, or the simple necessity to turn. Such costs cannot be stored as attributes of nodes or edges in the graph, and they cannot be handled correctly by shortest path algorithms without modifications. Turn costs can be represented by a pseudo-dual graph in a way that shortest path algorithms run without modifications. Although the idea is not new, it has not found much interest in the literature. The pseudo-dual graph is defined here in a new way, it is systematically investigated, and some practical applications are shown. Concentrating strictly on topology, it turns out that the pseudo-dual graph is conceptually cleaner and more efficient in route planning than alternative, currently used ways to deal with turn costs. The discussed applications are from the field of pedestrian navigation, which gave rise to this research.  

基于室内外定位的校园LBS研究

提出基于室内外定位的校园LBS平台总体框架，设计中心平台、移动终端和信息亭结构。给出室内定位系统，研究基于ZigBee的室内无线定位网络的部署原则和方法，建立基于室内外定位的校园LBS平台原型演示验证系统，该系统实现了终端定位、地图查询、三维浏览、导航与导游、跟踪监控、短信通知等功能。